Question

if a and b are the roots of equation 2x²+4x-5=0then find a+b and ab​

Answer 1

Answer:

Step-by-step explanation:

If alfa and beta are roots of equation then we know that

alfa + beta = -b/a

= -4/2

= -2

a + b = -2

alfa x beta = c/a

= -5/2

ab = -5/2

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Answer 2

If α and β are Zeroes of a Quadratic Polynomial, ax² + bx + c then :

●  α and β are roots of the Quadratic Equation, ax² + bx + c = 0

Given : α and β are zeros of Quadratic Polynomial 2x² - 4x + 5

Here : a = 2 and b = -4 and c = 5

●  α and β are roots of the Quadratic Equation, 2x² - 4x + 5 = 0

Consider : (α + β)³

 (α + β)³ = α³ + 3α²β + 3αβ² + β³

 (α + β)³ = α³ + 3αβ(α + β) + β³

 α³ + β³ = (α + β)³ - 3αβ(α + β)

α³ + β³ = -7

Therefore, the answer is -7